Telephone system



p 9 7- j G. w. KUHN 2,076,651

TELEPHONE SYSTEM Filed Jan. 28, 1936 A T TORNE Y Patented Apr. 13, 1937 UNITED STATES PATNT OFFICE TELEPHONE SYSTEM Application January 28, 1936, Serial No. 61,245

6 Claims.

This relates to telephone systems and has for its object to facilitate the establishment of notest connections.

In the application of F. A. Korn and O. Myers Serial 68,257, filed March 11, 1936, is set forth one method of establishing no-test connections in a telephone system employing cross-bar switches. In the disclosure of that application, connection is made with the wanted line by identifying and seizing the trunk connected with the subscribers line.

The present invention provides an improved means of identifying the trunk connected with a busy subscribers line. To this end, one terminal of a relay is connected with the test conductor of the wanted line and the other terminal connected successively to the test conductors of the busy trunks in the group having access thereto, the relay being shunted by the direct connection between the line and the trunk when the desired trunk is found.

The attached drawing shows a part of a primary line switch with two subscribers lines appearing therein, together with a part of the ter- 25 minating marker, by which connections are controlled.

When connection with a line is desired, the sleeve or test terminal of the line is connected to the marker through a line choice connector indi- 30 cated by relays IOI and I02. After the location of the line has been determined the sleeve or test conductors of the line links serving'the wanted line are connected through to the marker, relay I03 representing the line group control cir- 35 cuit, relay I04 the line choice connector and relay I05 the frame relay in the marker. Normally these link test circuits extend over the back contacts of relay I00 to channel test relays.

Assuming that connection with line I00 is de- 40 sired on a no-test basis, and that the line is busy with a connection over line link I00, when the line test circuit is closed, low resistance ground on the sleeve of link I 09 extends over the sleeve of cross point IIO, front contacts of re- 45 lays IOI and I02, back contact of relay III, windings of relays I07 and I08 to battery, relay I01 operating, to open the circuit of relay III. Since this connection was desired on a no-test basis, relay H3 is operated under the control of 50 the no-test incoming junctor on which the call originated. Therefore when relay I01 operates to indicate that the wanted line is busy, relay H2 is operated in place of the busy back relay. Relay I I2 causes circuit operations resulting in 55 the release of relay I01 and the operation of relay I I I thereby extending the sleeve of the wanted line over the front contact of relay III, front contact of relay II2 to the winding of relay II4. Relay H2 also operates relay I06 which transfers the test leads connected to the line links from the channel test relays to contacts of relay II5 and operates that relay to further extend these test leads to the relay chain. Relay II5 also connects relay I I6 to interrupter II'I through a pick-up arrangement (not shown) to insure a 10 sufficient interval between the operations of relay II5 and relay IIO.

When relay H6 operates for the first time it connects ground over the left back contact of relay I 2i to the winding of relay I and bat- 5 tery. Relay I20 looks through the winding of relay I ll to ground at the back contact of release relay I 30, but relay I2I does not operate until relay II6 releases to open the operating circuit of relay I20 which shunted relay I2I. 20 When relay II6 releases, relay I2I operates.

The second operation of relay H0 connects ground over the front contacts of relays H6 and I M left back contact of relay I23 to the winding of relay I22 and battery. Relay I22 also locks to the back contact of relay I and prepares the circuit forrelay I23 which is ineffective until relay II6 releases. In a similar manner relays I24 to I20 are operated successively. I 30 Until relay H0 operates, a circuit is closed from battery through the winding of relay I3I, back contact of relay I20, inner front contacts of relays I I5 and I06, lower contacts of relays I05, I 04 and I 03 to the sleeve conductor of line link I32. If the link is idle, relay I 3| does not opcrate, and when relay H0 operates, in turn operating relay I20, the circuit of relay I3I is transferred over the front contact of relay I20, back contact of relay I2I, middle front contacts of relays H5, I06, I05, I00 and I03 to the sleeve of line link I33. If link I30 is busy, relay I3I operates connecting its winding to the winding of relay H4 which is in turn connected to the sleeveof line I00 and ground. Relay H4 receives suificient current under this condition to operate.

With relay I22 operated, relay I3l is connected to the sleeve of the third link and the links are thus tested in succession. When relay I28 operates, relay I3I is connected over the front contacts of relays I20 to I20, right back contact of relay I29, outer front contacts of relays H5 and H0, inner front contacts of relays I05, I04 and I03 to the sleeve of link I09, to which, it was as- As indicated above, three conditions exist on.

the line links, the link may be idle, the link may be busy with some other line or the link may be busy with the wanted line.

In the first case neither relay I3I or relay H4 is operated, in the second case both relays are operated and in the third case relay I3I is operated but relay H4 not, thus providing a simple method of identifying the link serving the wanted line.

If it were desired, a simple stepping switch might be substitutedfor the relay chain without departing from the spirit of the invention.

What is claimed is:

'1. In a telephone system, a subscribers line, a group of trunks, means for connecting said line with one of said group of trunks, switching means, common control equipment having access to said line as a called line, to said trunks and to said switching'means, means in said control.

equipment for establishing a no-test connection withsaid-line by causing said switching means to connect with said one trunk, and means to identify said one trunk by connecting a relay to said subscribers line and successively connecting the trunks of said group to said relay.

7 2. In a telephone system, a subscribers line, agroup of trunks, means for connecting said line with one of said group of trunks, means for applying a busy potential to the test conductor of said line over the test conductor of said trunk, switching means,common control equipment having access to said line as a called line, to said trunks and to said switching means, means in said control equipment for establishing a notest connection with said line by causing said switching means to connect with said one trunk, and means to identify said one trunk comprising 'means for connecting a relay to the test conductor of said line and means to successively connect the test conductors of busy trunks of said group to said relay.

3. In a telephone system, a subscribers line, a group'of trunks, means for connecting said line with one of said group of trunks, means for applying the busy potential to the test conductor of said line over the test conductor of said trunk, switching means, common control equipment having access to said line as a called line, to said trunks and to said switching'means, means in said control equipment for establishing a no-test connection with said line by causing said switching means to connect with said one trunk and means to identify said one trunk, comprising means to connect a relay to said subscribers line, means responsive to said busy potential on the test conductor of said one trunk, means controlled by 7 said responsive means to connect saidrelay to the test conductor of said busy trunk and signaling meansoperated by said relay when connected to said trunk. v i v 1 4. In a telephone system, a subscribers line, a group of trunks, means for connecting said line with one of said group of trunks, switching means, common control equipment having access :to said line as a called line, to said trunks, and to said switching means, means in said control equipment for establishing a no-test connection with said line by causing said switching means to con- I to the test conductor of said line and means for successively connecting the test conductors of busy trunks to the other terminal of said relay.

5. In a telephone system, a subscribers line, a group of trunks, means for connecting said line with one of said group of trunks, means for applying a busy potential to the test conductor of said line over the test conductor of said trunk, switching means, common. control equipment having access to said line as 8. called line, to said trunks and to said, switching means, means in said control equipment for establishing a no-test connection with said line by causing said switching. means to connect with said one trunk and means to identify said one trunk, comprising a testing means, means for successively connecting said testing means to the test conductors of j ,means for connecting one terminal of said relay the trunks of said group, means controlled by said testing means when connected with busy trunks to connect said relay in parallel with said testing means, said-relay being responsive to connection with said one trunk to indicate its identity. v

6. In a telephone system, a subscribers line, a groupof trunks, means for connecting said line with one of said groupof trunks, means for applying a busy potential to the test conductor of said line over the test, conductor of said trunk,

ing access to said line as a called line, to said trunks and to said switching means, meansfin said control equipment for establishing a no-test connection with said line by causing said switcha ing means to connect with said one trunk, and

switching means common control equipment havrelay being operated when connected to a busy trunk other than said one trunk and shuntedby connection with said one trunk and means re sponsive to the non-operation of said first relay and the operation ofsaid second relay to indicate the identity or said one trunk.

GEORGE WILLIAM KUI- IN. 

